Process for forming metal-filled openings in low dielectric constant dielectric material while inhibiting via poisoning

• Main Authors: LU HONG-QIANG, ZHANG KAI, KUMAR KIRAN, CATABAY WILBUR G, HSIA WEI-JEN, KIM YONG-BAE, SCHOENBORN PHILIPPE, SCHINELLA RICHARD
• Format: Patent
• Language: English
• Published: 07.01.2003
• Edition: 7
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; SEMICONDUCTOR DEVICES

A composite layer of dielectric material is first formed over the integrated circuit structure, comprising a thin barrier layer of dielectric material, a layer of low k dielectric material over the barrier layer, and a thin capping layer of dielectric material over the layer of low k dielectric material. A photoresist mask, formed over the capping layer, is baked in the presence of UV light to cross-link the mask material. The composite layer is then etched through the resist mask using an etchant gas mixture including CO, but not oxygen. Newly exposed surfaces of low k dielectric material are then optionally densified to harden them. The resist mask is then removed using a plasma of a neutral or reducing gas. Exposed surfaces of low k dielectric material are then passivated by a low power oxygen plasma. Preferably, optional densification, mask removal, and passivation are all done in the same vacuum apparatus. The substrate is then solvent cleaned to remove etch residues and then annealed to degasify the low k dielectric material. The substrate is then RF cleaned and a thin layer of PVD titanium is then formed in the same chamber over the surfaces of the openings. CVD titanium nitride is then formed over the titanium in the same vacuum apparatus. The coated openings are then filled with aluminum, tungsten, or copper.